When you install Il-2 1946 from CD, it will be version 4.07m. Since the release of version 4.07m, plenty of patches have been added. To bring you up to current status, you need to apply the following patches in the following order:

since ubishop has changed site, and since direct2drive changed for gamefly, old downloaded versions of the game can't be activated. You must repurchase it through Ubisoft again, this time you get a DVD version at 4.07m, no activation, no cd key. You can also get the game on GOG.com for the same price of 9.99$ (usefull if you cannot get the ubisoft version because of your country), in case of a full system reinstallation. You can also use any working (a copy that you can start and play)stock copy of the game you might have as a backup. Those that have a physical DVD do not have any issues when reinstalling the game.

since ubishop has changed site, and since direct2drive changed for gamefly, old downloaded versions of the game can't be activated. You must repurchase it through Ubisoft again, this time you get a DVD version at 4.07m, no activation, no cd key. You can also get the game on GOG.com for the same price of 9.99$ (usefull if you cannot get the ubisoft version because of your country), in case of a full system reinstallation. You can also use any working (a copy that you can start and play)stock copy of the game you might have as a backup. Those that have a physical DVD do not have any issues when reinstalling the game.

Just adding some info here:
I just downloaded from shop.ubi.com for $4.99 and it came 4.07m without 4.08 file.
If you are not from the USA, and you want to buy from their bogus shop, you are forced to lie your country and put it USA.